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pavelkang

So what is this virtual focal plane?

Khryl

I think the virtual focal plane is the new focal plane that the image want to refocus on.

kayvonf

@Khryl @pavelkang. Correct.

The properties of the lens (focal length) and the distance between the lens and the sensor plane determine the plane of focus in the scene.

In a traditional camera, if we wanted to focus on a different plane out in the scene, we'd have to physically change the distance between the lens and the sensor. (That's what focusing your camera does! It moves the lens relative to the sensor.)

The main point here is that if you had a measurement of the light field in the camera (which we just talked about how to do using the microlens-sensor system), you no longer have to move the lens. Instead you can simulate the image that would have been observed by focusing on a different plane by, for each output pixel, integrating all the light rays fall within a diagonal region of ray space.

In this slide, the new plane we wish to focus on is called the virtual focal plane, since we're using computation to simulate the picture that would be have taken by a traditional camera if had been physically configured to focus on this plane.

whdawn

Am I under it correctly?

If the ray reaches sensor plane before converging, then the line will be top left to bottom right.

If it reaches sensor plane after converging, then the line will be top right to bottom left.

If it converges right on the sensor plane, then the line will be vertical.